Freieslebenite is a

sulfosalt Sulfosalt minerals are sulfide minerals with the general formula , where *A represents a metal such as copper, lead, silver, iron, and rarely mercury, zinc, vanadium *B usually represents semi-metal such as arsenic, antimony, bismuth, and rarely ...

mineral composed of

antimony Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient time ...

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

, and

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

. Sulfosalt minerals are complex sulfide minerals with the formula: A_mB_nS_p. The formula of freieslebenite is AgPbSbS₃. Freieslebenite was discovered in approximately 1773 in the Himmelsfurst mines of

Freiberg, Saxony Freiberg is a university and former mining town in Saxony, Germany. It is a so-called ''Große Kreisstadt'' (large county town) and the administrative centre of Mittelsachsen district. Its historic town centre has been placed under heritage ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. The mineral was initially called Schilf-Glaserz; however, in 1845 it was given the current name Freieslebenite after the Mining Commissioner of Saxony,

Johann Carl Freiesleben Johann Karl Freiesleben (14 June 1774 – 20 March 1846) was a German mineralogist and mining commissioner in Saxony. He was a childhood friend and correspondent of Alexander von Humboldt and was a promoter of stratigraphy and geognosy as taught by ...

(1774–1846).(Palache ''et al.'', 1944)

Structure

Freieslebenite is a superstructure of a PbS-type substructure. The

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystal, crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pat ...

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

with a space group P2₁/a, with a = 7.518(1), b = 12.809(4), c = 5.940(1) Å, β = 92.25(1)° and Z = 4(Ito, 1973). Sb has a trigonal-pyramidal coordination of S atoms, this structure isolates the SbS3 pyramids from themselves. The Sb–S distances are 2.431, 2.453 and 2.480(4) Å. Six S atoms are coordinated with Pb in a distorted octahedral arrangement. The Pb–S distances range from 2.806 to 3.167(4) Å. Ag has three nearest S neighbors at the distances 2.522, 2.575 and 2.687(4) Å. The AgS3 group is almost planar. A fourth S atom is at a distance of 2.928(4) Å from Ag, the Ag–S being closely perpendicular to the AgS3 plane (Cascarano et al., 1987). The crystal structure of freieslebenite was determined by Wuensch and Nowacki in 1967. Wuensch and Nowacki determined the crystal structure of freieslebenite using three-dimensional counter data, systematic consideration of all possible arrangements permitted by the subcell-supercell relationship and the method of key shifts (Ito, 1973).

Physical properties

Freieslebenite has a metallic luster and is opaque in transparency. The general colors for freieslebenite are gray, silver and white. It has a whitish-gray streak with a hardness of 2.5 on the Mohs scale. It has an imperfect cleavage and an irregular fracture. The density of freieslebenite is 6.20-6.23 g/cm³.

Geologic occurrence

The occurrence of freieslebenite is commonly found in

hydrothermal Hydrothermal circulation in its most general sense is the circulation of hot water (Ancient Greek ὕδωρ, ''water'',Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with th ...

locations. A major finding of freieslebenite was located in the Hiendelaencina mining district in Spain (Frias, 1991). Freieslebenite can also be located in North and South America and throughout Asia and Europe. Deposits of freieslebenite can generally be located in proximity with minerals

argentite In mineralogy, argentite (from the Latin ''argentum'', silver) is cubic silver sulfide (Ag2S), which can only exist at temperatures above 173 °C, 177 °C or 179 °C. When it cools to ordinary temperatures it turns into its monocl ...

siderite Siderite is a mineral composed of iron(II) carbonate (FeCO3). It takes its name from the Greek word σίδηρος ''sideros,'' "iron". It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus. Zinc, magnesium and ...

freibergite Freibergite is a complex sulfosalt mineral of silver, copper, iron, antimony and arsenic with formula . It has cubic crystals and is formed in hydrothermal deposits. It forms one solid solution series with tetrahedrite and another with argentoten ...

polybasite Polybasite is a sulfosalt mineral of silver, copper, antimony and arsenic. Its chemical formula is . It forms black monoclinic crystals (thin, tabular, with six corners) which can show dark red internal reflections. It has a Mohs hardness of 2.5 ...

, and

aramayoite Aramayoite ( IMA symbol: Ary) is a mineral with the chemical formula . Its type locality is Sud Chichas, Potosí, Bolivia.Aramayoite
o ...

Notes

References

*Palache, C., H. Berman, and C. Frondel (1944) Dana's system of mineralogy, (7th edition), v. I, 416–418. *Tetsuzo Ito and Werner Nowacki and (1974). The crystal structure of freieslebenite, PbAgSbS3* Zeitschrift für Kristallographie: Vol. 139, No. 1-2, pp. 85–102 *Frias, Martinez, J. (1991) The Hiendelaecina mining district (Guadalajara, Spain), Instituto Andaluz de Geologia Mediterranea, C.S.I.C *G. Cascarano, C. Giacovazzo, M. Luić, A. Pifferi und R. Spagna. (1987) 1-Phase seminvariants and Harker sections II. A new procedure. Zeitschrift für Kristallographie 179:1-4, 113-125

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